Fungicidal compositions



orrics monomer. comrosmons Paul ll. Carlisle, Wilmington, Bet, and Wilbie 8. Hinegardner, Niagara Falls, N. Y., assignors to E. I. du Pontde Nemourslb Company, Wilmington, Del., .a corporation of Delaware No Drawing. Application May 2, 1945,

Serial No. 581,834

7 Claims. (Cl. 167-22) l- 2 I This invention relates to volatile fungicides and constituents as shown in the examples presented more particularly to fungicides in which formaldchyde'vapor is an active fungicidal agent.

Formaldehyde vapor has been used extensively in the past to fumigate or disinfect rooms and other enclosed areas in an attempt to kill bacteria and fungi. Various devices such as formaldehyde candles. wh ch volatilize a formaldehyde larly harmful. and its disagreeable odor warns. 'anyone to keep out of the area.

However, formaldehyde, vapor is noteffectlve against many species of fungi, of which the common molds are examples, and relatively high concentrations are required together with careful control of humidity and temperature if it is to kill fungi in substan ial numbers. many species of fungi are not killed by any practically attainable concentration of formaldehyde vapor. Paraformaldehyde does not give off sumcient vapor when exposed at ordinary temperatunes to be of much value as a fungicide.

This invention has as an object a volatile'fungicide that will kill essentially all fungi in an enclosed area and protect valuable materials from damage or destruction by fungus growth. A further object is to prepare an effective fungicide from paraformaldehyde that will effectively prevent the growth of. all fungi when allowed to evepalate in an enclosed area. A further object is to devise a fungicide. based on paraformaldchyde that does not require special means to insure suiilcient fungicidalvapor in the enclosed space. Another object isan improved method for destroying or preventing the growth of fungi. Still other objects will be apparent from the following description.

These objects are accomplished by the discovery that certain chlorine derivatives of trimethyl acetonitrile hereinafter described, when mixed with paraformaldehyde and the mixture allowed to evaporate in an enclosed space, kill essentially all species of fungi. The effect is much more than the additive fungicidal properties of the two Furthermore.

later. This additional effect, known as synergism, is unexpectedly large in the case of p raformaldedyde. No other material than paraformaldehyde. of a large number examined, showed such a. high degree of synergism when paired with the chlorinated trimethyl-acetonitriles. The maximumv synergistic effect is ch- ,tained when paraformaldehyde makes up -90 per cent of the mixture. Still larger paraform concentrations may be usedif desired; that is, the chlorinated trimethyl acetonitrlle content may be less than 10 per cent and as low as 5 per cent. However. at such low concentrations of the chlorinated 'trimethyl acetonitrile the synergistic action is less marked. When paraformaldehyde becomes the minor constituent of the mixture of two materials; that is, 25 per cent or less, such mixtures are usually no longer completely fungicidal even though they are still more highly fungicidal than paraformaldehyde alone. The preferred concentration is -90 per cent paraf'ormaldehyde.

The chlorine derivatives used in this invention are new compounds which are described and claimed in the copending patent application by Oliver W. Cass, Serial No. 580,701, filed March .2,

Monochlorotrimethyl acetonitrile (C HaCI-CN) ich o t me yl acetonitrlle (C4H1Clz-CN) Trichlorotrimethyl acetonitrile (Cd-IaCla-CN) structurally the compounds can be designated by the formula: 1

where :c=1 to 3 and and z=0 to 3, and the sum of at, 2/. and z is not greater than 3. x The monochloro derivative is a liquid which boils at about C. The dichloro and trichloro derivatives exist in several isomeric modifications. all of which are suitable for the present invention. One of the two dichloro isomers is a volatile solid, which melts at 69-70 C. and boils at 207-208 C. The other dichloro isomer is a liquid, boiling in the range-of 205 to2l0 C. The trichloro derivatives are liquids, boiling in the range of 225-235 C. s These chlorin derivatives of trimethy1 acetonitrile may be made by chlorinating trimethyl 1 examples:

aasaaao acetonitrile misc-H) in the presence of light at a temperature of 70 to 180 C. The products be separated from the crude chlorination not by fractional distillation. The solid dichloro isomer. is obtained by cooling the dichloro fraction. whereupon the solid isomers separat by crystallization and can be filtered ofi. In practicing the present invention, the solid dichloro isomer is preferred. However, the

liquid homers, or any desiredmixture of them,

may be used with good results. Such liquid mixture also may contain the solid dichloro isomer, which is soluble in the liquid isomers. when the liquid chlorine derivatives are mixed with powdered or granular paraformaldehyde. the latter absorbs the liquid to forms composition having the properties-of a solid when the para- !ormaldehyde concentration is 50 per cent by weight or higher. I

We have discovered that the above-described when mixed in the proportion of Huber cent by weight with paraformaldehyde, exhibit the above-described synergistic sheet and mm a completely fungicidal vapor when allowed to vaporize into an enclosed space.

The invention is illustrated by the following six resistant species of fungi equally spaced in a circular pattern: namely. Monilia "sp.. Aspergillus niaer, Penicilium sp., Bpicaria sp., Rhizopus sp.. and Gliocladium flmbriatum. One pellet of the material to be tested as a fungicide was placed in the cup and the halfzthat had been inoculated inverted over the first part and their edges sealed together with adhesive tape. The Petri dishes were incubated at 80 C. for five days. The amount of growth for each species was recorded daily for the five days. Any funginot growing during this time was transferred to fresh nutrient agar away from the fungicide to determine whether that species had been killed or merely prevented from growing; that is, to determine whether the action was fungicidal or merely fungistatic to that species of fungi.

In a number of tests one half of the species grew in the dish containing paraformaldehyde pellets. Four of the six species grew in thedish with dichlorotrimethyl acetonitrile and a fifth grew on transfer to a new medium. The dish with the mixed 'paraformaldehyde-dichlorotrimethyl acetonitrile pellet had no growth, and

none of the species grew on transfer to a new when the amount of the mixture was reduced so that the vapor concentration could not exceed one gram of vapor per-l000 cc. of air. the mixed fungicide still prevented all fungi growth and none grew on transfer. At this latter concentration the individual separate constituents.

' chlorine derivatives of trimethylacetonitrile.

- cellulose were substituted for the ten fungi used- The nutrient agar was inoculated separately with paraformaldehyde and dichlorotrimethyl acetonitrile. had almost no killing effect on the fungi. In a third test at a concentration of one gram of vapor of the mixture per 10,000 cc. only two species of fungi grew.

Example I The three types of pellets described in Example 1 were further tested in similar chambers made from six-inch Petri dishes, but with ten additional resistant tropical fungi; namely, llionilia crcua, Aspergillus sp-. Aspergillus flaws, Penicilium sp. (2 specimens) Stachybotrys sp., Srorofrichum roseum, Alternarla sp., Aspergillus chevalieri,and Mucor sp. When paraformaldehyde was used alone, only two of the fungi were killed. Dichlorotrimethyl acetonitrilc killed only one. However, "a mixture of the two compounds containing 0-50 per cent dichlorotrimethyl acetonitrile killed all ten fungi in every test. This test was also repeated with the mixture of paraform'aldehyde and dichlorotrimethyl acetonitrile at 21-35 0. (room temperature). Again no species grew after inoculation nor upon transfer.

maps 3 The tests of Example 2 were repeated with amixture of '15 per cent paraformaldehyde and per cent dichlorotrimethyl acetonitrile, but ten resistant molds from the tropics that attack in Example 2; The mixture was completely fungicidal, though neither constituent alone killed P r cent of them.

Example 4 Example I was repeated on a mixture of paraformaldehyde 25 per cent+dichlorotrlmethyl acetonitrile 75 per cent. This mixture allowed only two speciesof fungi to grow.

Example 5 Example 4 was repeated, except that the paraformaldehyde concentration was decreased to 10 per cent. The mixture allowed two species to grow. Example 8 The tests of Example 1 were repeated with a mixture of 90 per cent paraformaldehyde and 10 per cent monochlorotrlmethyi acetonitrlle. The mixture was completely fungicidal, though paraformaldehyde alone under the ,same conditions killed only three fungi and the monochlorotrimethyl acetonitrile alone only three fungi.

Example 7 The tests of Example 1 were repeated with a mixture of 75 per. cent paraformaldehyde and 26 per cent trlchlorotrlmethyl acetonitr-ile. The

mixture was completely fungicidal. Trichlorotrimethyl acetonitrilealone permitted three of the species to grow and a fourth-one on'transfer, and paraformaldehyde alone permitted the growth of three species. The trichlorotrimethyl acetonitrile used in these tests was a mixture of the trichloro isomers.

The fungicidal compositions of matter herein described are solids that can be used asa powtin or for convenience can be compressed into pellets. A small amount of lubricant such as magnesium stearate can be added to improve pelleting. Except for the lubricant. these pellets are almost completely volatile and leave essentiallyno'residuefordispcaal. v

' diluents, or other fungicidal materials may be added. For some purposes, insecticides or; known bactericides may also be added. The-mixtures can be incorporated in suitable nonaqueous liquids for spraying purposes, for example in a liquid hydrocarbon.

For some purposes, dlchlorotrimethyl acetonitrile can be used alone, i. e. in the absence of paraformaldehyde in combination with various diluents or other conventional ingredients as described above, to prepare fungicidal compositions.

These pellets or powdered mixtures offer a most convenient means for obtaining a fungicidal atmosphere in an enclosed space, but this method of making use of this synergistic effect is intended in no way to limit the scope of this invention. The two constituents can be introduced separately into the enclosed space without previous mixing. Thus, formaldehyde vapor can be added by any means, and -50 per cent of the second constituent can be introduced before or after the formaldehyde. If this mixed vapor is kept in the enclosed space by any means, it will still be fungicidal.

These mixtures are fungicidal'within the range of temperature that fungi commonly grow and at any higher temperature desired.

The fungicidal compositions of matter described under this invention may be used to protect materials from fungi (molding) in any enclosed area where fungi grow. Materials stored in damp basements especially in hot weather nearly always mold. Leathergoods, which are very apt to mold, can-be preserved by these mixtures. Things packed for tropical shipment can be kept free of fungi. Molds in garbage-pails can be prevented by this means. These volatile fungicides do not need to be placed in the, materials .to be protected. since the vapor alone will protect. In this way they are superior to contact fungicides. They are particularly effective in warm, damp places, since water vapor does not react with them to destroy their fungicidal properties, and fungi are prone to grow rapidly under such conditions.

The fungicidal mixtures claimed herein are essentially completely fungicidal under conditions usually encountered in enclosed spaces and are easy to apply. Elaborate or expensive equipment is not required. The fungicidal mixtures claimed herein are sufiiciently harmless for general use.

We claim:

1. A fungicidal composition comprising a mixture of paraformaldehyde and a chlorine derivative of trimethyl aceton-itrile having the formula C4H(9:r)C1r-CN, where x=1 to 3.

2. The composition according to claim 1 which contains not less than 50 per cent by weight of paraformaldehyde. v

3.. A fungicidal composition comprising a mixture of paraformaldehyde and a dichlorotrimethyl p r cent by I form-aldehyde and at least one chlorine derivative of trimethyl acetonitrile having the formula C iH(e '=)Clx-CN, where 12:1 to 3.

6. The method for preventing growth of fungi in an enclosed space, which comprises simultaneously introducing into said space vapors of formaldehyde and a dichlorotrime'thyl acetonitrile in such proportion that the formaldehyde vapor constitutes atleast 50 per cent by weight of the combined vapors.

'7. The method for preventing growth of fungi in an enclosed space which comprises simultaneously introducing into said space vapors of formaldehyde and solid dichlorotrimethyl acetonitrlle in such proportion that the formaldehyde vapor constitutes from 50 per cent to about per cent by weight of the combined vapors.

PAUL J. CARL-ISLE. WILBIE s. HINEGARDNER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Name Date Peters Mar. 14, 1844 Number 36, June 1943, page 421. 

